EFI and Electronic Ignition Initial Start Up Questions

Bruce,

I installed a fuse panel that operates off of a relay. When the key is on and I believe cranking the panel has power. I say I believe because I will
double check tomorrow while it is physically cranking. I believe I confirmed this today, but it never hurts to triple check the cranking mode. I
checked 12v on the pink wire to the computer while cranking earlier today.

That being said, thank very much for your help and input.

Take care,
Tom K.
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
On my '76 there's a purple wire that goes from the start terminal on the ignition switch to the neutral switch on the steering column. The other side
of the neutral switch is also a purple #12, and it goes directly to the starter. I took the cranking signal to the EFI from that wire at the starter
and ran it through a 3A fuse to pin C3 on the ECM.
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Bill,

1977 Birchaven had an IGN spare spade in the fuse panel. I used that to operate the relay on the new ign fuse bus. I attached the pink wire at the
ALDL to this panel. When the key is on and through the cranking process the pink wire gets power. The fuel pump opertes and fuel pressure is up.

I did add a new to me spark control dist. I have the original connector attached and one wire to the tach location. It may be my after market Tach,
which means I have no connection to the EBL. I will have to review to see if there is any wiring concerns at that location?

Thank you and everyone for their help.

Take care,
Tom
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
If you have a low oil pressure shut off switch that could be causing you
trouble as well depending upon how it is wired. I had issues with my Howell
+ Ebl upon initial startup until I removed the low oil pressure switch that
I had installed at the same time.

Sully
Bellevue wa

> Bill,
>
> 1977 Birchaven had an IGN spare spade in the fuse panel. I used that to
> operate the relay on the new ign fuse bus. I attached the pink wire at the
> ALDL to this panel. When the key is on and through the cranking process
> the pink wire gets power. The fuel pump opertes and fuel pressure is up.
>
> I did add a new to me spark control dist. I have the original connector
> attached and one wire to the tach location. It may be my after market Tach,
> which means I have no connection to the EBL. I will have to review to see
> if there is any wiring concerns at that location?
>
> Thank you and everyone for their help.
>
> Take care,
> Tom
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
I would refer you to Randy V, but knowing you mixed things up, even Randy
will have a hard time analyzing your issue.
On all ECM need signal from the Tach off the distributor to know that the
engine is rotating.

> Bill,
>
> 1977 Birchaven had an IGN spare spade in the fuse panel. I used that to
> operate the relay on the new ign fuse bus. I attached the pink wire at the
> ALDL to this panel. When the key is on and through the cranking process
> the pink wire gets power. The fuel pump opertes and fuel pressure is up.
>
> I did add a new to me spark control dist. I have the original connector
> attached and one wire to the tach location. It may be my after market Tach,
> which means I have no connection to the EBL. I will have to review to see
> if there is any wiring concerns at that location?
>
> Thank you and everyone for their help.
>
> Take care,
> Tom
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
No worries Jim K.,

I built and flew my helicopter, which was a hand full and sold it last year. The GMC is one of my new hobbies and I love working on it.

With the tips and pointers everyone is supplying, I am confident I will find the glitch.

Thanks for your assistance.

Take care,
Tom K.
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
Here's a description of the starting sequence for GM ECMs that I picked up somewhere.
Quote:
> STARTING MODE
>
> When you first key on the ignition, the ECM loads the information off the PROM chip and performs a quick, self-diagnostic test. Some later ECMs
> also pulsed the injectors during this period to aid in what is known as “quick start” (obviously helping the engine startup more quickly). All
> of this happens in a very short amount of time, usually much less than 1 second after the key is turned on. Also during this period the fuel pump
> is activated for 2 seconds to “prime” the system. Next, the ECM waits until it receives reference pulses from the distributor (or crank
> sensor). Once it receives reference pulses (indicating the engine is turning over) it will use air/fuel ratio values stored in the cranking fuel
> pulse tables (in the PROM programming) which are based on the coolant temperature to determine how much pulse width (amount of injector ON time) it
> needs to command the fuel injectors open. The lower the coolant temperature, the richer the Air/Fuel ratio. The higher the coolant temperature,
> the leaner the Air/Fuel ratio. Ignition spark advance and IAC valve position output functions use similar tables.

I misread the cranking signal pin earlier; it should be pin C9, not C3. I'll change the post as well.
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Make sure that BAT wire is installed in the cap. The 2pin connector is installed in the cap. Disconnect any tach. from the distributor. The 4 wire
connector must be hooked up . The module(7 pin) in the distributor is what gives you spark and the signal to fire the injectors when cranking and
under a preset RPM some ware around 500 RPM. If you are not getting a spark and injector pulse(check with a Node light) you may have a module that has
failed.
--
Michael Orlandi
Fairfield, Ca
1973 GMC Canyonlands
Lenzi knuckles/ hubs
 
Guys,

Thank you so much for all the help. Mike I believe you are right. I called Howell and spoke with Troy. Within 5 min he diagnosed and believes it is
the coil, but could also be the module based on you observations. I will get a new Cap and Module. Does anyone have a preferred part number that works
well with the Howell set up?

I have to run out today, but plan on enjoying the day in the shop tomorrow. I would love to get it running well tomorrow.

thank you again for all the help, it is very much appreciated.

Take care,
Tom K
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
I like Delco . 1987 Olds 5.0L Vin Y I think. The aftermarket ones are a crap shoot .
--
Michael Orlandi
Fairfield, Ca
1973 GMC Canyonlands
Lenzi knuckles/ hubs
 
Michael,
Node light is a tool that i keep in my Cad turbo unit as it is a quick way
to know if the injectors are getting power,
I'm getting so old, I forgot that I keep it in the coach.
Thanks for suggesting that.

> Guys,
>
> Thank you so much for all the help. Mike I believe you are right. I called
> Howell and spoke with Troy. Within 5 min he diagnosed and believes it is
> the coil, but could also be the module based on you observations. I will
> get a new Cap and Module. Does anyone have a preferred part number that
> works
> well with the Howell set up?
>
> I have to run out today, but plan on enjoying the day in the shop
> tomorrow. I would love to get it running well tomorrow.
>
> thank you again for all the help, it is very much appreciated.
>
> Take care,
> Tom K
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
Springfield ignition.

Sully
Bellevue wa

> Guys,
>
> Thank you so much for all the help. Mike I believe you are right. I called
> Howell and spoke with Troy. Within 5 min he diagnosed and believes it is
> the coil, but could also be the module based on you observations. I will
> get a new Cap and Module. Does anyone have a preferred part number that
> works
> well with the Howell set up?
>
> I have to run out today, but plan on enjoying the day in the shop
> tomorrow. I would love to get it running well tomorrow.
>
> thank you again for all the help, it is very much appreciated.
>
> Take care,
> Tom K
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
> IF you have the EBL upgrade, all that is required to pulse the injectors is pulses from the distributor. I asked this question to BobR of
> DynamicEFI while remotely troubleshooting another GMCer's issues and this was his response:
>
>
> > Can you advise me the input signal requirements that must be met for the EBL to start firing the injectors during startup.
>
> >>All that is required is the distributor reference pulses (DRPs). The crank signal is not required, that just lets the ECM know when to test the
> fuel pump relay.

Good to know for certain; thanks Bruce! Do you know what the fuel pump relay test is? I suppose it tests for fuel pump relay power on pin B2 while
cranking for diagnostics.
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Guys,

More mental puzzle for those in the know.

I got good spark. Switched Distributor cap and coil.

Fuel pump came on pegged fuel pressure gauge at 30 pounds. No fuel through injectors. Engine runs when fuel is poured in throttle body.

I cracked a fuel line at the gauge to see if I was in fact getting pressure. Yes I am, but don't know how much as the gauge is now toast and remains
pegged at 30 pounds.

Some where I read about physically tapping the injectors with a wooden screw driver. Any tips from this point are welcome.

Spark is no problem, Pump sounds and pressure seems to exist. When the engine quits I hear a squeal from around the throttle body?

Should I take an electric reading at each injector connector while cranking? Also crack the supply line at the throttle body to check for fuel?

I think I am down to a simple fuel issue at the throttle body. I have no way to measure fuel pressure at this time.

Thanks,
Tom
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
dDont worry about the pressure now.
make the injectors pulse .
The pressure of 30 is at the entrance, the built in regulator gets it down
to around 12 .
Make sure the tack sensor is tied in, otherwise no pulse of injectors.

> Guys,
>
> More mental puzzle for those in the know.
>
> I got good spark. Switched Distributor cap and coil.
>
> Fuel pump came on pegged fuel pressure gauge at 30 pounds. No fuel through
> injectors. Engine runs when fuel is poured in throttle body.
>
> I cracked a fuel line at the gauge to see if I was in fact getting
> pressure. Yes I am, but don't know how much as the gauge is now toast and
> remains
> pegged at 30 pounds.
>
> Some where I read about physically tapping the injectors with a wooden
> screw driver. Any tips from this point are welcome.
>
> Spark is no problem, Pump sounds and pressure seems to exist. When the
> engine quits I hear a squeal from around the throttle body?
>
> Should I take an electric reading at each injector connector while
> cranking? Also crack the supply line at the throttle body to check for fuel?
>
> I think I am down to a simple fuel issue at the throttle body. I have no
> way to measure fuel pressure at this time.
>
> Thanks,
> Tom
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
> dDont worry about the pressure now.
> make the injectors pulse .
> The pressure of 30 is at the entrance, the built in regulator gets it down
> to around 12 .
> Make sure the tack sensor is tied in, otherwise no pulse of injectors.
>

>
>> Guys,
>>
>> More mental puzzle for those in the know.
>>
>> I got good spark. Switched Distributor cap and coil.
>>
>> Fuel pump came on pegged fuel pressure gauge at 30 pounds. No fuel
>> through injectors. Engine runs when fuel is poured in throttle body.
>>
>> I cracked a fuel line at the gauge to see if I was in fact getting
>> pressure. Yes I am, but don't know how much as the gauge is now toast and
>> remains
>> pegged at 30 pounds.
>>
>> Some where I read about physically tapping the injectors with a wooden
>> screw driver. Any tips from this point are welcome.
>>
>> Spark is no problem, Pump sounds and pressure seems to exist. When the
>> engine quits I hear a squeal from around the throttle body?
>>
>> Should I take an electric reading at each injector connector while
>> cranking? Also crack the supply line at the throttle body to check for fuel?
>>
>> I think I am down to a simple fuel issue at the throttle body. I have no
>> way to measure fuel pressure at this time.
>>
>> Thanks,
>> Tom
>> --
>> Tom & Oki Katzenberger,
>> Kingsville, Maryland,
>> 1977 23' Birchaven, 455 C.I.D.
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
>
>
> --
> Jim Kanomata ASE
> Applied/GMC, Newark,CA
> jimk
> http://www.gmcrvparts.com
> 1-800-752-7502
>


--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
Jim K,

Thanks Jim.

Injectors now firing and engine runs great!

Thank you and everyone for all the help. I very much look forward to putting faces to all the name of those that I am very grateful for.

I wish everyone a very healthy and Merry Christmas.

Take care,
Tom K.
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
Tom, so I've read the WHOLE thread. What was wrong and what fixed it ? Inquiring
minds need/want to know. LOL
Thanks
--
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
 
Loose nut behind the wheel? (Grin)
Jim Hupy ( Been there, Done that, Got the T-Shirt)
Salem, Oregon

> Tom, so I've read the WHOLE thread. What was wrong and what fixed it ?
> Inquiring
> minds need/want to know. LOL
> Thanks
> --
> DAVE KING
> lurker, wannabe
> Toronto, Ontario, Canada
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
Yes... Quote:
> What was wrong and what fixed it ?

Quote:
> Tom says: "I did add a new to me spark control dist. I have the original connector attached and one wire to the tach location. It may be my after
> market Tach, which means I have no connection to the EBL. I will have to review to see if there is any wiring concerns at that location?"

Some more questions... What is a 'spark control distributor'? HEI? HEI with 8-pin module, pigtail, and 4-pin weatherpac connector that connects the
new harness and back to the ECM? What is the 'original connector? One of the connectors for power, ground and tach connectors at the coil or the 4-pin
harness connector?


--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
You must log in or register to reply here.
GMCMI Spring 2026 Rally
Get your shine on at www.cruzingear.co

Share this page

Share this page
Top Bottom
Back